Webs of material are often used in a variety of industries and in a variety of ways. These materials can include paper, multi-layer paperboard, and other products manufactured or processed in sheets or other webs. As a particular example, long sheets of paper or other materials can be manufactured and collected in reels.
Fiber orientation (FO) refers to the dominant alignment direction of fibers in a paper sheet or other web. Fiber orientation can be expressed by a fiber orientation angle and a fiber orientation index. These two properties can be measured by performing a “cut and dry” test, which is illustrated in FIG. 1. A circular sample 102 of a web is desiccated in a laboratory, and the original circular sample 102 typically shrinks into a desiccated sample 104 having an elliptical shape. The angle (α) between the machine direction and the major axis of the ellipsoid is used as the fiber orientation angle. The ratio of the major and minor axes (l/s) is used as the fiber orientation index. “Machine direction” or “MD” refers to a direction in which the web moves (along its length). In contrast, “cross direction” or “CD” refers to a direction across the web (along its width).
Several quality properties are highly related to fiber orientation, such as web strength and dimensional stability. A poor fiber orientation property can cause quality issues for paper products, such as paper jams in sheet-fed devices, mis-register in color printing, twist in multi-layer boards, weakening of corrugated containerboard, and poor runability of high-speed newsprint.